Ultrasound evaluation of the femoral trochlea in newborns: incidence of trochlear dysplasia and associated risk factors.

This study aimed to describe the femoral groove morphology using ultrasound in children under 6 months, estimate the incidence of trochlear dysplasia, and evaluate associated risk factors. A prospective study included 298 patients who underwent universal ultrasound screening for hip dysplasia [developmental dysplasia of the hip (DDH)] and knee ultrasound. Measurements of sulcus angle (SA), trochlear depth (TD), and trochlear facet asymmetry (TFA) were analyzed. Trochlear dysplasia was considered present if the ASO was ≥159°. Reproducibility was assessed using the intraclass correlation coefficient (ICC) in 60 knees. Logistic regression adjusted for confounders, presenting odds ratios (OR) and 95% confidence intervals (CI). Significance was set at P  < 0.05. Analysis included 596 knees (298 patients). Females accounted for 51% of patients, with 7% having breech presentation, 4.4% DDH, 6.4% family history of DDH, and 5% family history of patellofemoral instability. ICC showed excellent agreement for SA and TD, but poor for TFA. Trochlear dysplasia incidence was 3% (9/298; 67% bilateral). Median (IQR) values were 147.5 (144.0-150.5) for SA, 2.4 (2.2-2.8) for TD, and 1.1 (1.0, 1.1) for TFA. Breech presentation (OR, 9.68; 95% CI 1.92-48.71, P  = 0.006) and concomitant DDH (OR 6.29, 95% CI 1.04-37.78, P  = 0.044) were associated with trochlear dysplasia. Ultrasound effectively evaluates femoral groove morphology and diagnoses trochlear dysplasia in newborns. Trochlear dysplasia incidence was 3%, with a 10-fold higher risk in breech presentation and 6-fold higher risk in concomitant DDH. Standardized screening and timely treatment protocols should be further investigated. Level of evidence: Diagnostic Level II.